1. Field of the Invention
The present invention relates to an apparatus for automatically exchanging a number of record medium cassettes with respect to a plurality of recording and reproducing devices. Such an apparatus may be advantageously used in a mass storage system of computer and broadcasting equipment. It should be noted that in the present specification, the record medium cassette means a cassette or cartridge of any shape and construction containing any kind of a record medium on and from which any kind of information can be recorded and reproduced.
2. Related Art Statement
A known mass storage system called MSS comprises a plurality of cassette exchange units, each including a cassette storing means for storing a number of record medium cassettes, a recording and reproducing means for recording and reproducing information on and from the record medium cassettes, a cassette transporting means for transporting the record medium cassettes between the cassette storing means and the recording and reproducing means, and a controlling means for controlling said cassette storing means, recording and reproducing means and cassette transporting means, and each of said plurality of cassette exchange units is connected with a host computer by means of an interface cable such as RS-232C cable and SCSI cable.
FIG. 9 is a schematic view showing a known apparatus for automatically exchanging record medium cassettes. In each of four cassette exchange units 1-4, there are provided cassette storing means 5, recording and reproducing means 6, controlling means 7 and cassette transporting means not shown. Each controlling means 7 of the cassette exchange units 1-4 are respectively connected with a host computer 8 by means of interface cables 9-12. The cassette storing means 5, recording and reproducing means 6 and cassette transporting means in respective cassette exchange units 1-4 are controlled by the host computer 8 such that the record medium cassettes are transported between the cassette storing means and the recording and reproducing means to effect the automatic cassette exchange with respect to the recording and reproducing means.
In the known automatic cassette exchange apparatus, the respective cassette exchange units 1-4 are controlled by the host computer 8 separately, and therefore it is rather difficult for the host computer 8 to control a plurality of cassette exchange units in a parallel mode. Particularly, when it is required to add one or more cassette exchange units for increasing a total storage capacity, the parallel control becomes much more complicated and difficult. In other words, the control sequence of the host computer has to be changed to a large extent.
Furthermore, the recording and reproducing means installed in respective one of the cassette exchange units 1-4 could not be used for record medium cassettes installed in another cassette exchange units, and thus when a command from the host computer 8 is concentrated to one cassette exchange unit, a waiting time is prolonged. That is to say, when the recording or reproducing operation for a certain record medium cassette in a certain cassette exchange unit has been finished and another record medium cassette installed in the same cassette exchange unit is required to be set in the recording and reproducing means, the latter cassette could not be transported into the recording and reproducing means until the former cassette has been completely brought back into the cassette storing means. Therefore, there is a rather long waiting time between successive recording or reproducing operations.
The present invention has for its object to provide a novel and useful apparatus for automatically exchanging record medium cassettes, in which the above mentioned problems can be removed by transporting the record medium cassettes among a plurality of cassette exchange units and any desired number of cassette exchange units can be added without difficulty.
According to the invention, an apparatus for automatically exchanging a number of record medium cassettes comprises:
a plurality of cassette exchange units, each including a cassette storing means for storing a plurality of record medium cassettes, a recording and reproducing means for recording and reproducing information on and from record medium cassettes, a first cassette transporting means for transporting the record medium cassettes between the cassette storing means and the recording and reproducing means, and a controlling means for controlling said cassette storing means, recording and reproducing means and first cassette transporting means; and PA1 a second cassette transporting means for bridging said plurality of cassette exchange units and transporting the record medium cassettes between said cassette exchange units.
In a preferable embodiment of the automatic cassette exchanging apparatus according to the invention, said plurality of cassette exchange units are controlled by a host computer.
In the automatic cassette exchanging apparatus according to the invention, since a plurality of cassette exchange units each including a number of record medium cassettes are coupled with each other by means of the second cassette transporting means, the record medium cassettes can be freely transported between the exchange units. That is to say, a certain record medium cassette installed in the cassette storing means of a certain cassette exchange unit is transported by the first cassette transporting means into the second transporting means, and then is further transported into another cassette exchange unit by the second transporting means.